Seeing this occasionally in the gate recently, instance spawn fails with VirtualInterfaceCreateException after timing out 300 seconds waiting for the 'network-vif-plugged' event from neutron. The event never arrives (before or after we begin waiting).
Here's log excerpts showing how it looks [1]:
Sep 23 06:10:44.144477 ubuntu-focal-rax-iad-0026631025 nova-compute[110797]: DEBUG nova.compute.manager [None req-6d0b7dcf-7f96-47d2-8673-626abdd275b7 tempest-TestSnapshotPattern-20482801 tempest-TestSnapshotPattern-20482801-project] [instance: 487a3a37-fe41-447d-bc77-9ab3fce47473] Preparing to wait for external event network-vif-plugged-9129f5b9-2940-44c2-8d44-04c46df5fe49 {{(pid=110797) prepare_for_instance_event /opt/stack/nova/nova/compute/manager.py:280}}
[...]
Sep 23 06:15:44.961239 ubuntu-focal-rax-iad-0026631025 nova-compute[110797]: WARNING nova.virt.libvirt.driver [None req-6d0b7dcf-7f96-47d2-8673-626abdd275b7 tempest-TestSnapshotPattern-20482801 tempest-TestSnapshotPattern-20482801-project] [instance: 487a3a37-fe41-447d-bc77-9ab3fce47473] Timeout waiting for [('network-vif-plugged', '9129f5b9-2940-44c2-8d44-04c46df5fe49')] for instance with vm_state building and task_state spawning: eventlet.timeout.Timeout: 300 seconds
Logstash query:
http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22Instance%20failed%20to%20spawn%3A%20nova.exception.VirtualInterfaceCreateException%3A%20Virtual%20Interface%20creation%20failed%5C%22%20AND%20tags%3A%5C%22screen-n-cpu.txt%5C%22&from=7d
[1] https://paste.opendev.org/show/809546
Another hit on stable/ussuri in the nova-live-migration job:
https:/